PRACTICE IN BIOLOGY  -  STUDENT REPORT

NAME: Raffaela Pastore Meneguetti                           DATE: April 28, 2008

TITTLE: 

Photosynthetic Pigments

INTRODUCTION: 

A photosynthetic pigment or antenna pigment is a pigment that is present in chloroplasts or photosynthetic bacteria and captures the light energy necessary for photosynthesis.Chlorophyll a is the most common of the six, present in every plant that performs photosynthesis. The reason that there are so many pigments is that each absorbs light more efficiently in a different part of the spectrum. Chlorophyll a absorbs well at a wavelength of about 400-450 nm and at 650-700 nm; chlorophyll b at 450-500 nm and at 600-650 nm. Xanthophyll absorbs well at 400-530 nm. However, none of the pigments absorbs well in the green-yellow region, which is responsible for the abundant green we see in nature.

Green plants have six closely-related photosynthetic pigments (in order of increasing polarity):

  • Carotene - an orange pigment
  • Xanthophyll - a yellow pigment
  • Chlorophyll a - a blue-green pigment
  • Chlorophyll b - a yellow-green pigment
  • Phaeophytin a - a gray-brown pigment
  • Phaeophytin b - a yellow-brown pigment
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Electromagnetic Spectrum

Light behaves as if it were composed of "units" or "packets" of energy that travel in waves. These packets are photons.        

The wavelength of light determines its color. For example, The wavelength of red is about 700 nm and the wavelength of blue light is about 470 nm.

Graph.1: Made by Raffaela Pastore Meneguetti

Visible light is a part of a larger spectrum of radiation called the electromagnetic ...

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